The spatiotemporal evolution of urbanization of the countries along the Belt and Road Initiative using the compounded night light index

The Belt and Road Initiative (BRI) region is one of the regions with great economic vitality and potential in the world today. Exploring the spatiotemporal evolution of the urbanization in the region has important practical significance for its development. This study extracted urban light based on nighttime light data. Additionally, on a national scale, based on the quantitative relationship between the compounded night light index (CNLI) and the level of urbanization composite index (Cf) (R2 = 0.75, p < 0.01), the CNLI can reflect the level of urbanization, and the urbanization of the countries along the BRI from 2005 to 2015 was obtained. The methods of global and local spatial autocorrelation and weighted standard deviational ellipse were employed to demonstrate the patterns of the spatiotemporal evolution of urbanization in the BRI region. The results indicate the following. (1) From 2005 to 2015, urbanization showed an overall upward trend. The center of gravity moved 318 km southeastward; the spatial layout was northwest-southeast; among them, Central and Eastern Europe, China, and Southeast Asia played an important role. (2) Urbanization in the BRI countries had significant spatial dependence, showing a significant high-high local agglomeration pattern in West Asia and a clear low-low local agglomeration pattern in Eastern Europe, which was strongly affected by regional policies.